Display device

ABSTRACT

A display device includes, on a substrate, light emitting elements each formed by sequentially stacking a first electrode layer, an organic layer including a light emission layer, and a second electrode layer and arranged in first and second directions which cross each other, a drive circuit including drive elements that drive light emitting elements, and a wiring extending in the first direction, and an insulating layer disposed in a gap region sandwiched by the light emitting elements neighboring in the second direction and having a recess or a projection. The wiring is disposed in an overlap region overlapping with the recess or the projection in the insulating layer in a thickness direction, in the gap region, and the second electrode layers in the light emitting elements neighboring in the second direction are separated from each other by the recess or the projection in the insulating layer.

CROSS REFERENCES TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 14/512,028, filed on Oct. 10, 2014, which application is acontinuation of U.S. patent application Ser. No. 13/782,130, filed onMar. 1, 2013, and issued as U.S. Pat. No. 8,866,133 on Oct. 21, 2014,which application is a continuation of U.S. patent application Ser. No.13/159,577 filed on Jun. 14, 2011 and issued as U.S. Pat. No. 8,399,892on Mar. 19, 2013, which claims priority to Japanese Priority PatentApplication JP 2010-147859 filed in the Japan Patent Office on Jun. 29,2010, the entire content of which is hereby incorporated by reference.

BACKGROUND

The present application relates to a display device having a lightemitting element of a self-emitting type including an organic layer.

In recent years, as a display device replacing a liquid crystal display,an organic EL display using an organic light emitting element of aself-emitting type including an organic layer is being practically used.Since the organic EL display is of a self-emitting type, the view angleis wider than that of liquid crystal or the like, and the organic ELdisplay has sufficiently high response also to a high-definitionhigh-speed video signal.

With respect to an organic light emitting element, an attempt forimproving display performance was made by introducing a resonatorstructure and controlling light generated by a light emission layer byimproving purity of light colors, increasing light emission efficiency,or the like (refer to, for example, WO 01/39554). For example, asillustrated in FIG. 14, an organic light emitting element Z10 of a topemission type that extracts light from a face (top surface) on the sideopposite to a substrate employs a structure that an anode electrode Z13,an organic layer Z14, and a cathode electrode Z16 are sequentiallystacked over the substrate via a drive transistor ZTr1. Light from theorganic layer Z14 is multiple-reflected between the anode electrode Z13and the cathode electrode Z16. The drive transistor ZTr1 drives theorganic light emitting element Z10. A pixel drive circuit is constructedby the drive transistor ZTr1 together with a signal line Z120A and thelike. In FIG. 14, Z111 denotes a substrate, Z212 indicates a gateinsulating film of the drive transistor ZTr1, Z217 indicates aprotection film made of silicon nitride or the like, and Z218 indicatesa planarization film made of polyimide or the like. Further, Z17 denotesa metal layer as an auxiliary wiring, Z24 denotes an element isolationinsulating layer, Z18 denotes a protection film made of silicon nitrideor the like, and Z19 is a sealing substrate made of a transparentmaterial.

SUMMARY

In a general organic EL display, from the viewpoint of assurance ofsimplicity of a configuration and manufacture easiness, the cathodeelectrode Z16 is formed so as to extend over an entire image displayregion. In other words, the cathode electrode Z16 is provided commonlyto all of the organic light emitting elements Z10 disposed in a matrixin the image display region. Consequently, a part of the cathodeelectrode Z16 overlaps with the signal line Z120A in the thicknessdirection, and unnecessary parasite capacitance Cz is formed (refer toFIG. 14). Since the signal line Z120A is a path for supplying voltage ofa video signal according to luminance information from an externalsignal supply source, even the unnecessary parasite capacitance Cz isformed, signal delay is caused. In some cases, it is difficult todisplay an accurate image corresponding to a video signal.

As a method of solving such a problem, there may be a method ofincreasing the distance in the thickness direction between the signalline Z120A and the cathode electrode Z16 (disposing them far from eachother in the thickness direction). However, it disturbs compactificationof the entire organic EL display, so that it is unrealistic.

It is therefore desirable to provide a display device capable ofdisplaying more excellent image display performance even with a simpleconfiguration.

A display device according to an embodiment of the application includes,on a substrate: a plurality of light emitting elements each formed bysequentially stacking a first electrode layer, an organic layerincluding a light emission layer, and a second electrode layer andarranged in first and second directions which cross each other; a drivecircuit including a plurality of drive elements that drive the pluralityof light emitting elements and a wiring extending in the firstdirection; and an insulating layer disposed in a gap region sandwichedby light emitting elements neighboring in the second direction andhaving a recess or a projection. The wiring is disposed in an overlapregion overlapping the recess or the projection in the insulating layerin a thickness direction, in the gap region. The second electrode layersin the light emitting elements neighboring in the second direction areseparated from each other by the recess or the projection in theinsulating layer.

In the display device according to an embodiment of the application, thewiring included in the drive circuit that drives the light emittingelements is disposed in the overlap region overlapping the recess or theprojection in the insulating layer in a thickness direction, in the gapregion sandwiched by light emitting elements in the second direction.Moreover, the second electrode layers are separated from each other inthe second direction by the recess or the projection in the insulatinglayer. Consequently, between a wiring and the first and second electrodelayers constructing the light emitting element, formation of unnecessaryparasite capacitance is avoided or the size of the parasite capacitanceis sufficiently reduced. In addition, manufacture easiness at the timeof manufacturing a display device having such a wiring and a secondelectrode layer is also assured.

In a display device as an embodiment of the application, the insulatinglayer having the recess or the projection is provided in the gap regionbetween neighboring light emitting elements to separate the secondelectrode layers, and the wiring included in the drive circuit thatdrives the light emitting elements is disposed in the gap region. Withthe configuration, the facing portions between the wiring and the firstand second electrode layers do not exist in the thickness direction, sothat formation of unnecessary parasite capacitance is avoided, or thesize of the parasite capacitance is sufficiently reduced. As a result,occurrence of unintended signal delay is suppressed, and accurate imagedisplay corresponding to a predetermined video signal is realized.

Additional features and advantages are described herein, and will beapparent from the following Detailed Description and the figures.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a diagram illustrating the configuration of a display deviceaccording to an embodiment.

FIG. 2 is a diagram illustrating an example of a pixel drive circuitshown in FIG. 1.

FIG. 3 is a plan view illustrating the configuration of a display regionshown in FIG. 1.

FIG. 4 is a cross section illustrating the configuration of the displayregion shown in FIG. 1.

FIG. 5 is a plan view illustrating the configuration of a pixel drivecircuit formation layer shown in FIG. 4.

FIG. 6 is an enlarged cross section illustrating an organic layer shownin FIG. 5.

FIG. 7 is an enlarged cross section illustrating a configuration exampleof a projection in an element isolation insulating layer shown in FIG.4.

FIG. 8 is an enlarged cross section illustrating another configurationexample of the projection in the element isolation insulating layershown in FIG. 4.

FIG. 9 is a schematic diagram illustrating a plane shape of a secondelectrode layer provided on a substrate of FIG. 1 and a wiring patternin the periphery of the second electrode layer.

FIG. 10 is an enlarged cross section of a connection part illustrated inFIG. 3.

FIG. 11 is a cross section illustrating the configuration of a main partof a display device as a first modification.

FIG. 12 is a cross section illustrating the configuration of a main partof a display device as a second modification.

FIG. 13 is a cross section illustrating the configuration of a main partof a display device as a third modification.

FIG. 14 is a cross section illustrating the configuration of a displaydevice as a related art.

DETAILED DESCRIPTION

Embodiments of the present application will be described below in detailwith reference to the drawings.

Modes for carrying out the present application (hereinbelow, calledembodiments) will be described in detail below with reference to thedrawings.

FIG. 1 illustrates the configuration of a display device using anorganic light emitting element according to an embodiment. A displaydevice is used as an organic light emitting color display device of avery thin type or the like. In the display device, a display region 110is formed on a substrate 111. In the periphery of the display region 110on the substrate 111, for example, a signal line drive circuit 120, ascan line drive circuit 130, and a power supply line drive circuit 140as drivers for displaying video images are formed.

In the display region 110, a plurality of organic light emittingelements 10 (10R, 10G, and 10B) disposed two-dimensionally in a matrixand a pixel drive circuit 150 for driving the elements are formed. Inthe pixel drive circuit 150, a plurality of signal lines 120A (120A1,120A2, . . . , 120Am, . . . ) are disposed in the column direction (Ydirection) and a plurality of scan lines 130A (130A1, . . . 130An, . . .) and a plurality of power supply lines 140A (140A1, . . . 140An, . . .) are disposed in the row direction (X direction). Any one of theorganic light emitting elements 10R, 10G, and 10B is provided at theintersecting point of each signal line 120A and each scan line 130A. Thesignal lines 120A are connected to the signal line drive circuit 120,the scan lines 130A are connected to the scan line drive circuit 130,and the power supply lines 140A are connected to the power supply linedrive circuit 140.

The signal line drive circuit 120 supplies voltages of video signalsaccording to luminance information supplied from a signal supply source(not shown) to the organic light emitting elements 10R, 10G, and 10Bselected via the signal line 120A.

The scan line drive circuit 130 is constructed by a shift register forsequentially shifting (transferring) a start pulse in synchronizationwith an input clock pulse. The scan line drive circuit 130 scans theorganic light emitting elements 10R, 10G, and 10B row by row at the timeof writing video signals to the elements and sequentially supplies scansignals to the scan lines 130A.

The power supply line drive circuit 140 is constructed by a shiftregister or the like for sequentially shifting (transferring) a startpulse in synchronization with an input clock pulse. The power supplyline drive circuit 140 properly supplies any of first and secondpotentials which are different from each other to the power supply lines140A in synchronization with the scan on the row basis of the scan linedrive circuit 130. By the operation, a conduction state or anon-conduction state of a drive transistor Tr1 which will be describedlater is selected.

The pixel drive circuit 150 is provided in a hierarchical layer (a pixeldrive circuit formation layer 112 which will be described later)existing between the substrate 111 and the organic light emittingelement 10. FIG. 2 illustrates a configuration example of the pixeldrive circuit 150. As illustrated in FIG. 2, the pixel drive circuit 150is an active-type drive circuit having the drive transistor Tr1, a writetransistor Tr2, a capacitor (retention capacitor) Cs existing betweenthe drive transistor Tr1 and the write transistor Tr2, and the organiclight emitting element 10. The organic light emitting element 10 isconnected in series to the drive transistor Tr1 between the power supplyline 140A and a common power supply line (GND). Each of the drivetransistor Tr1 and the write transistor Tr2 is a general thin filmtransistor (TFT) and may have, for example, an inverted-staggeredstructure (so-called bottom-gate type) or a staggered structure(top-gate type). The structure is not limited.

For example, the drain electrode of the write transistor Tr2 isconnected to the signal line 120A, and a video signal is supplied fromthe signal line drive circuit 120 to the write transistor Tr2. The gateelectrode of the write transistor Tr2 is connected to the scan line130A, and a scan signal from the scan line drive circuit 130 is suppliedto the write transistor Tr2. Further, the source electrode of the writetransistor Tr2 is connected to the gate electrode of the drivetransistor Tr1.

For example, the drain electrode of the drive transistor Tr1 isconnected to the power supply line 140A, and the drive transistor Tr1 isset to either the first or second potential of the power supply linedrive circuit 140. The source electrode of the drive transistor Tr1 isconnected to the organic light emitting element 10.

The retention capacitor Cs is formed between the gate electrode of thedrive transistor Tr1 (the source electrode of the write transistor Tr2)and the source electrode of the drive transistor Tr1.

FIG. 3 illustrates a configuration example of the display region 110extending in an XY plane. It shows the planar configuration, as viewedfrom above, of the display region 110 in a state where a secondelectrode layer 16, a protection film 18, and a sealing substrate 19(which will be described later) are removed. In the display region 110,the plurality of organic light emitting elements 10 are aligned in amatrix. More specifically, a metal layer 17 as an auxiliary wiring layeris provided in a lattice shape, and the organic light emitting elements10R, 10G, and 10B are disposed one by one in regions defined by themetal layer 17. Each of the organic light emitting elements 10R, 10G,and 10B includes a light emitting region 20 whose outline is specifiedby an element isolation insulating layer 24. In FIG. 3, a broken-linerectangle surrounding the light emitting region 20 indicates a firstelectrode layer 13 (which will be described later) included in theorganic light emitting element 10. The organic light emitting elementl0R emits red light, the organic light emitting element 10G emits greenlight, and the organic light emitting element 10B emits blue light. Theorganic light emitting elements 10 emitting the same color are arrangedin one line in the Y direction, and the organic light emitting elements10 aligned by colors in the Y direction are repeatedly disposed in the Xdirection. Therefore, one pixel is constructed by a combination of theorganic light emitting elements 10R, 10G, and 10B neighboring in the Xdirection.

In a plurality of gap regions VZ sandwiched by the organic lightemitting elements 10 in the X direction, the signal lines 120A (notillustrated in FIG. 3) extending in the Y direction are provided. Asillustrated in FIG. 3, in the element isolation insulating layer 24,some openings 24K are provided in a part of a region overlapping themetal layer 17 existing between organic light emitting elementsneighboring in the Y direction. In the region surrounded by the openings24K, a connection part 21 for achieving contact between the metal layer17 and the second electrode layer 16 of the organic light emittingelement 10 is constructed. The number of organic light emitting elements10 arranged in the X and Y directions is set arbitrarily and is notlimited to the number illustrated in FIG. 3. One pixel may beconstructed by four or more organic light emitting elements, and organiclight emitting elements that emit white light may be further provided.

FIG. 4 illustrates a schematic configuration in an XZ section takenalong line IV-IV in FIG. 3, in the display region 110. As illustrated inFIG. 4, in the display region 110, a light emitting element formationlayer 12 including the organic light emitting element 10 is formed onthe substrate 11 in which the pixel drive circuit formation layer 112 isprovided on the substrate 111. On the organic light emitting element 10,the protection film 18 and the sealing substrate 19 are provided inorder. The organic light emitting element 10 is obtained by stacking, inorder from the side of the substrate 111, the first electrode layer 13as an anode electrode, an organic layer 14 including a light emissionlayer 14C (which will be described later), and the second electrodelayer 16 as a cathode electrode. The organic layer 14 and the firstelectrode layer 13 of each organic light emitting element 10 areisolated by the element isolation insulating layer 24. On the otherhand, the second electrode layer 16 is provided commonly to all of theorganic light emitting elements 10. The metal layer 17 is buried by theelement isolation insulating layer 24 except for the regionscorresponding to the openings 24K.

The element isolation insulating layer 24 is provided so as to fill thegaps between the first electrode layer 13 and the organic layer 14 inthe neighboring organic light emitting elements 10. The elementisolation insulating layer 24 is made of an organic material such aspolyimide, assures the insulation between the first electrode layer 13,and the second electrode layer 16 and the metal layer 17, and accuratelydefines the light emission region 20 in the organic light emittingelement 10.

The protection film 18 covering the organic light emitting element 10 ismade of an insulating material such as silicon nitride (SiNx). Thesealing substrate 19 provided on the protection film 18 is to seal theorganic light emitting element 10 together with the protection film 18,an adhesive layer (not illustrated) and the like, and is made of amaterial such as transparent glass transmitting light generated in thelight emission layer 14C.

With reference to FIGS. 5 and 6 in addition to FIG. 4, the detailedconfiguration of the substrate 11 and the organic light emitting element10 will be described. The organic light emitting elements 10R, 10G, and10B have the common configurations except for a part of theconfiguration of the organic layer 14. In the following, the commonconfigurations will be described.

FIG. 5 is a schematic view illustrating a planar configuration of thepixel drive circuit 150 provided for the pixel drive circuit formationlayer 112, in one organic light emitting element 10. FIG. 4 correspondsto a section taken along line IV-IV illustrated in FIG. 5. FIG. 6 is apartly enlarged section of the organic layer 14 illustrated in FIG. 4.

The substrate 11 is obtained by providing the substrate 111 made by aglass or silicon (Si) wafer or made of resin or the like with the pixeldrive circuit formation layer 112 including the pixel drive circuit 150.On the surface of the substrate 111, a metal layer 211G as the gateelectrode of the drive transistor Tr1, a metal layer 221G as the gateelectrode of the write transistor Tr2, and a part of the signal line120A (FIG. 5) are provided as metal layers in the first hierarchicallayer. The metal layers 211G and 221G and the signal line 120A arecovered with a gate insulating film 212 made of silicon nitride, siliconoxide, or the like.

In the drive transistor Tr1, a channel layer 213 which is asemiconductor thin film made of amorphous silicon or the like isprovided in a part of a region corresponding to the metal layer 211G. Onthe channel layer 213, an insulating channel protection film 214 isprovided so as to occupy a channel region 213R as a center region. Inregions on both sides of the channel protection film 214, a drainelectrode 215D and a source electrode 215S made by an n-typesemiconductor thin film made of n-type amorphous silicon or the like areprovided. The drain electrode 215D and the source electrode 2155 areisolated from each other by the channel protection film 214, and theirend faces are apart from each other with the channel region 213R inbetween. Further, a metal layer 216D as a drain wire and a metal layer216S as a source wire are provided as metal layers in a secondhierarchical layer so as to cover the drain electrode 215D and thesource electrode 215S. The metal layers 216D and 216S have, for example,a structure in which a titanium (Ti) layer, an aluminum (Al) layer, anda titanium layer are stacked in order. The write transistor Tr2 has aconfiguration similar to that of the drive transistor Tr1. In FIG. 5,the metal layer 221G as the metal layer in the first hierarchical layerand the metal layer 226D (drain wire) and the metal layer 226S (sourcewire) as metal layers in the second hierarchical layer are illustratedas components of the write transistor Tr2.

As the metal layers in the second hierarchical layer, the scan line 130Aand the power supply line 140A are provided in addition to the metallayers 216D and 226D and the metal layers 216S and 226S. Although thedrive transistor Tr1 and the write transistor Tr2 having theinverted-staggered structure (so-called bottom-gate type) have beendescribed above, they may have the staggered structure (so-calledtop-gate type). The signal line 120A is provided as the metal layer ofthe second hierarchical layer in the region other than the crossingpoint of the scan line 130A and the power supply line 140A.

The pixel drive circuit 150 is entirely covered with a protection film(passivation film) 217 made of silicon nitride or the like, and aninsulating planarization film 218 is provided on the protection film217. Desirably, the surface of the planarization film 218 has extremelyhigh flatness. The fine connection hole 124 is provided in a partialregion in the planarization film 218 and the protection film 217 (referto FIG. 5). Since the planarization film 218 is thicker particularlythan the protection film 217, preferably, the planarization film 218 ismade of a material having high pattern precision like an organicmaterial such as polyimide. The connection hole 124 is filled with thefirst electrode layer 13 to make conduction to the metal layer 216Sconstructing the source line of the drive transistor Tr1.

The first electrode layer 13 formed on the planarization film 218 alsohas the function as a reflecting layer and is desirable to be made of amaterial having reflectance as high as possible in order to increase thelight emission efficiency. For this purpose, the first electrode layer13 is made of a high-reflectance material such as aluminum (Al) oraluminum neodymium (A1Nd). Aluminum has low resistance to a developingsolution used for a developing process performed at the time of formingthe opening 24K in the element isolation insulating layer 24 and iscorrosion-prone. On the other hand, AlNd has high resistance to adeveloping solution and is not corrosion-prone. Preferably, the firstelectrode layer 13 has a single-layer structure made of A1Nd or atwo-layer structure of “Al layer (lower layer)/AlNd layer (upper layer)”of an aluminum layer and AlNd. In particular, the two-layer structure of“Al layer (lower layer)/AlNd layer (upper layer)” is preferable for areason that resistance is lower than that of a single AlNd layer. Thethickness of the first electrode layer 13 as a whole is, for example,100 nm to 1,000 nm both inclusive. Another configuration is alsopossible such that the first electrode layer 13 has a two-layerstructure, the upper layer (a layer which is in contact with the organiclayer 14) is made of the above-described high-reflectance material, andthe lower layer (a layer which is in contact with the planarization film218) is made of a low-reflectance material such as molybdenum (Mo) orits compound (alloy). By providing a layer having high light absorptionrate on the face which is in contact with the pixel drive circuitformation layer 112 in which the drive transistor Tr1 and the writetransistor Tr2 are provided, unnecessary light such as outside light andlight leaked from the organic light emitting element 10 can be absorbed.As described above, the first electrode layer 13 is formed so as tocover the surface of the planarization film 218 and fill the connectionhole 124.

The organic layer 14 is densely formed on the entire light emittingregion 20 defined by the element isolation insulating layer 24. Forexample, as illustrated in FIG. 6, the organic layer 14 has aconfiguration in which a hole injection layer 14A, a hole transportlayer 14B, a light emission layer 14C, and an electron transport layer14D are stacked in order from the side of the first electrode layer 13.The layers other than the light emission layer 14C may be provided asnecessary.

The hole injection layer 14A is a buffer layer for increasing the holeinjection efficiency and to prevent leakage. The hole transport layer14B is provided to increase the efficiency of transporting holes to thelight emission layer 14C. The light emission layer 14C is provided togenerate light by recombination of electrons and holes by application ofelectric field. The electron transport layer 14D is provided to increasethe efficiency of transporting electrons to the light emission layer14C. An electron injection layer (not illustrated) made of LiF, Li₂O, orthe like may be provided between the electron transport layer 14D andthe second electrode layer 16.

The configuration of the organic layer 14 varies according to the lightemission colors of the organic light emitting elements 10R, 10G, and10B. The hole injection layer 14A in the organic light emitting element10R has, for example, a thickness of 5 nm to 300 nm both inclusive andis made of 4,4′,4″-tris(3-methylphenylamino) triphenylamine (m-MTDATA)or 4,4′,4″-tris(2-naphthylphenylamino) triphenylamine (2-TNATA). Thehole transport layer 14B in the organic light emitting element 10R has,for example, a thickness of 5 nm to 30 nm both inclusive and is made ofbis[(N-naphthyl)-N-phenyl]benzidine (α-NPD). The light emission layer14C in the organic light emitting element 10R has, for example, athickness of 10 nm to 100 nm both inclusive and is made of a materialobtained by mixing 40 volume % of2,6-bis[4-[N-(4-methoxyphenyl)-N-phenyl]aminostyryl]naphthalene-1,5-dicarbonitrile(BSN-BCN) to 8-quinolinol aluminum complex (Alq₃). The electrontransport layer 14D of the organic light emitting element 10R has, forexample, a thickness of 5 nm to 300 nm both inclusive and is made ofA1q₃.

The hole injection layer 14A of the organic light emitting element 10Ghas, for example, a thickness of 5 nm to 300 nm both inclusive and ismade of m-MTDATA or 2-TNATA. The hole transport layer 14B of the organiclight emitting element 10G has, for example, a thickness of 5 nm to 300nm both inclusive and is made of α-NPD. The light emission layer 14C inthe organic light emitting element 10G has, for example, a thickness of10 nm to 100 nm both inclusive and is made of a material obtained bymixing 3 volume % of coumarin 6 to A1q₃. The electron transport layer14D in the organic light emitting element 10G has, for example, athickness of 5 nm to 300 nm both inclusive and is made of A1q₃.

The hole injection layer 14A in the organic light emitting element 10Bhas, for example, a thickness of 5 nm to 300 nm both inclusive and ismade of m-MTDATA or 2-TNATA. The hole transport layer 14B in the organiclight emitting element 10B has, for example, a thickness of 5 nm to 300nm both inclusive and is made of α-NPD. The light emission layer 14C inthe organic light emitting element 10B has, for example, a thickness of10 nm to 100 nm both inclusive and is made of spiro 6Φ. The electrontransport layer 14D in the organic light emitting element 10B has, forexample, a thickness of 5 nm to 300 nm both inclusive and is made ofA1q₃.

The second electrode layer 16 has, for example, a thickness of 5 nm to50 nm both inclusive and is made of a single metal element or alloy ofaluminum (Al), magnesium (Mg), calcium (Ca), sodium (Na), or the like.Among them, an alloy of magnesium and silver (MgAg alloy) or alloy ofaluminum (Al) and lithium (Li) (AlLi alloy) is preferable. The secondelectrode layer 16 is provided, for example, commonly to all of theorganic light emitting elements 10R, 10G, and 10B and is disposed so asto face the first electrode layer 13 of each of the organic lightemitting elements 10R, 10G, and 10B. Further, the second electrode layer16 is formed so as to cover not only the organic layer 14 but also theelement isolation insulating layer 24.

As illustrated in FIG. 4, the element isolation insulating layer 24 hasa projection 24T in a gap region VZ. The gap region VZ is, as describedabove, a region sandwiched by the organic light emitting elements 10which are neighboring in the X direction as the arrangement direction ofthe organic light emitting elements 10 for emitting different colorrays.

FIG. 7 is an enlarged view of a portion around the projection 24Tillustrated in FIG. 4. The signal line 120A is disposed in an overlapregion DZ overlapping the projection 24T in the element isolationinsulating layer 24 in the thickness direction (Z direction) in the gapregion VZ. The second electrodes 16 in the organic light emittingelements 10 neighboring in the X direction are isolated from each otherby the projection 24T in the element isolation insulating layer 24. Oneor both of angles α and β formed by a top surface 24TS and a side wall24WS are 90° C. or less (preferably, less than 90° C.). Concretely, theprojection 24T has, for example, a rectangular sectional shape asillustrated in FIG. 7 or an inverted trapezoidal shape as in anotherconfiguration example illustrated in FIG. 8. Due to the existence of theprojection 24T, even in the case where the material of the secondelectrode layer 16 is deposited in a lump on the entire display region110 by, for example, evaporation, the second electrode layers 16 in theneighboring organic light emitting elements 10 are naturally isolatedfrom each other. Since each of the angles α and β at edges 24EG is 90°C. or less, a material to be deposited is not easily deposited in theregion. As a result, the second electrode layer 16 provided in the lightemission region 20 and a metal layer 16Z covering the top surface TS ofthe projection 24T are divided at the edge 24EG. In particular, when theprojection 24T has an inverted-trapezoidal sectional shape asillustrated in FIG. 8, the second electrode layers 16 are divided fromeach other more reliably.

Since the second electrode layer 16 is divided in the overlap region DZ,its plane shape is a shape of rectangles whose longitudinal directioncorresponds to the Y direction (refer to FIG. 9). FIG. 9 is a schematicdiagram showing a plane shape of the second electrode layer 16 providedon the substrate 111 and wiring patterns in the periphery of the layer16. As illustrated in FIG. 9, in the display device, a plurality ofsecond electrode layers 16 extend in the Y direction so as to penetratethe display region 110 and are also arranged in the X direction.Further, both ends of each of the plurality of second electrode layers16 are connected to a common wiring pattern and are connected to acommon power supply line GND (refer to FIG. 2) via pads P1 to P4.

FIG. 10 is an enlarged section of a portion around the connection part21 illustrated in FIG. 3. The metal layer 17 is formed on the surface ofthe planarization film 218 like in the first electrode layer 13 andfunctions as an auxiliary wiring which compensates a voltage drop in thesecond electrode layer 16 as a main electrode. As described above, themetal layer 17 is covered with the second electrode layer 16 in theconnection part 21 in the region of the opening 24K and is electricallyconnected to the second electrode layer 16 (refer to FIG. 10). Asillustrated in FIGS. 4, 7, and 8, the metal layer 17 in the gap regionVZ is provided in a region other than the overlap region DZ in the gapregion VZ and extends in parallel to the signal line 120A.

In the case where the metal layer 17 does not exist, the potential ofthe second electrode layer 16 connected to the common power supply lineGND (refer to FIG. 2) varies between the organic light emitting elements10R, 10G, and 10B due to voltage drops according to the distances fromthe power supply (not illustrated) to the organic light emittingelements 10R, 10G, and 10B, and conspicuous variations tend to occur.Such variations in the potential of the second electrode layer 16 causeluminance unevenness in the display region 110 and are not preferable.Even in the case where the screen of the display device is enlarged, themetal layer 17 functions to suppress the voltage drop from the powersupply to the second electrode layer 16 to the minimum and suppressoccurrence of such luminance unevenness.

For example, the display device is manufactured as follows. A method ofmanufacturing the display device of the embodiment will be describedwith reference to FIGS. 4 to 7.

First, on the substrate 111 made of the above-described material, thepixel drive circuit 150 including the drive transistor Tr1 and the writetransistor Tr2 is formed. Concretely, first, a metal film is formed by,for example, sputtering on the substrate 111. After that, by patterningthe metal film by, for example, photolithography, dry etching, or wetetching, the metal layers 211G and 221G and a part of the signal line120A are formed on the substrate 111. Subsequently, the entire surfaceis covered with the gate insulating film 212. Further, on the gateinsulating film 212, a channel layer, a channel protection film, a drainelectrode and a source electrode, the metal layers 216D and 226D, andthe metal layers 216S and 226S are formed in order in a predeterminedshape. Together with the formation of the metal layers 216D and 226D andthe metal layers 216S and 226S, a part of the signal line 120A, the scanline 130A, and the power supply line 140A are formed as the second metallayer. At this time, a connection part for connecting the metal layer221G and the scan line 130A, a connection part for connecting the metallayer 226D and the signal line 120A, and a connection part forconnecting the metal layers 226S and 211G are formed in advance. Afterthat, by covering the whole with the protection film 217, the pixeldrive circuit 150 is completed. An opening is formed by dry etching orthe like, in a predetermined position on the metal layer 216S in theprotection film 217.

After formation of the pixel drive circuit 150, a photosensitive resinwhose main component is, for example, polyimide is coated on the entiresurface by spin coating or the like. By performing the photolithographyprocess on the photosensitive resin, the planarization film 218 havingthe connection hole 124 is formed. Concretely, for example, by selectiveexposure and development using a mask having an opening in apredetermined position, the connection hole 124 communicated with theopening provided in the protection film 217 is formed. After that, theplanarization film 218 may be sintered as necessary to thereby obtainthe pixel drive circuit formation layer 112.

Further, the first electrode layer 13 and the metal layer 17 made of theabove-described predetermined material are formed. Concretely, the metalfilm made of the above-described material is formed on the entiresurface by, for example sputtering and, after that, a resist pattern(not illustrated) in a predetermined shape is formed by using apredetermined mask on the stack film. Using the resist pattern as amask, the metal film is selectively etched. The first electrode layer 13is formed so as to cover the surface of the planarization film 218 andfill the connection hole 124. The metal layer 17 is formed on thesurface of the planarization film 218 so as to surround the periphery ofthe first electrode layer 13 and so as not to overlap the signal line120A. Preferably, the metal layer 17 is formed together with the firstelectrode layer 13 by using a material of the same kind as that of thefirst electrode layer 13.

After that, the element isolation insulating layer 24 is formed so as tofill the gap between the neighboring first electrode layers 13 and so asto cover the metal layer 17. In the operation, the opening 24K is formedin a predetermined position. Further, the projection 24T extending inthe Y direction is formed in the overlap region DZ overlapping thesignal line 120A. The projection 24T is formed by exposing processusing, for example, a halftone mask or by performing multiple exposureprocess.

Subsequently, by sequentially stacking the hole injection layer 14A, thehole transport layer 14B, the light emission layer 14C, and the electrontransport layer 14D each made of the above-described predeterminedmaterial and having the above-described thickness so as to completelycover the exposed part in the first electrode layer 13 by, for example,the evaporation method, the organic layer 14 is formed. Further, byforming the second electrode layer 16 on the entire surface so as to beopposed to the first electrode 13 with the organic layer 14 therebetweenand so as to cover the metal layer 17 in the connection part 21, theorganic light emitting element 10 is completed. In the formation, thethickness of the second electrode layer 16 is adjusted so as to bedivided in the X direction by the edge 24EG of the projection 24T.

After that, the protection film 18 made of the above-described materialis formed to cover the entire surface. Finally, an adhesive layer isformed on the protection film 18 and, using the adhesive layer, thesealing substrate 19 is adhered to the protection film 18. As a result,the display device is completed.

In the display device obtained in such a manner, a scan signal issupplied via the gate electrode (metal layer 221G) in the writetransistor Tr2 from the scan line drive circuit 130 to each of thepixels, and an image signal from the signal line drive circuit 120 isretained in the retention capacitor Cs via the write transistor Tr2. Onthe other hand, the power supply line drive circuit 140 supplies a firstpotential higher than a second potential to each of the power supplylines 140A in synchronization with the scan on the row basis of the scanline drive circuit 130. As a result, the conduction state of the drivetransistor Tr1 is selected and the drive current Id is injected to eachof the organic light emitting elements 10R, 10G, and 10B, so that holesand electrons are recombined to generate light. The light ismultiply-reflected between the first electrode layer 13 and the secondelectrode layer 16, passes through the second electrode layer 16, theprotection film 18, and the sealing substrate 19, and is extracted.

As described above, in the embodiment, the second electrode layers 16neighboring in the X direction are isolated from each other by theprojection 24T in the element isolation insulating layer 24 in the gapregion VZ. Moreover, the signal line 120A included in the pixel drivecircuit 150 for driving the organic light emitting element 10 isdisposed in the overlap region DZ overlapping the projection 24T in thethickness direction (Z direction) in the gap region VZ and extends inthe Y direction. Consequently, an unnecessary parasitic capacitor isprevented from being formed between the signal line 120A and the firstand second electrode layers 13 and 16 constructing the organic lightemitting element 10 or the size of the parasitic capacitor issufficiently reduced. As a result, occurrence of unintended signal delayis suppressed, and accurate image display corresponding to apredetermined video signal is realized.

In the embodiment, the plurality of second electrode layers 16 extendingin the Y direction and arranged in the X direction are naturally formedby forming the projection 24T in the element isolation insulating layer24 in advance and depositing the predetermined material so as to coverthe entire display region 110. Therefore, without performinghigh-precision patterning process, the second electrode layer 16 isproperly and easily disposed in a region which is not overlapped withthe signal line 120A (the region other than the overlap region DZ).

There is another method of forming a plurality of the second electrodelayer 16 having the shape of a plurality of rectangles by using a metalmask having slits. However, since the second electrode layer 16 isnarrow in width (the limit slit width is about 20 μm), it is difficultto manufacture the metal mask itself corresponding to the width. Even ifsuch a metal mask is manufactured, there is concern that the strength ofthe metal mask is insufficient. Further, the alignment precision of themetal mask is also limited. In contrast, in the embodiment, theprojection 24T in the element isolation insulating layer 24 is formed byexposure or multiple exposure using, for example, a halftone mask.Consequently, high-precision position control is not demanded forformation of the projection 24T.

The present application has been described above by the embodiment, theapplication is not limited to the foregoing embodiment but may bevariously modified. For example, in the foregoing embodiment, byproviding the projection 24T in the overlap region DZ in the elementisolation insulating layer 24, the neighboring second electrode layers16 are isolated. However, the application is not limited to theembodiment. For example, as in first and second modifications of FIGS.11 and 12, recesses 24G1 and 24G2 may be provided in the overlap regionDZ. Alternatively, like in a third modification illustrated in FIG. 13,both of a recess 24G3 and projections 24T1 and 24T2 may be provided forthe element isolation insulating layer 24 in the overlap region DZ. Inany case, effects similar to those of the foregoing embodiment areobtained.

Although overlap between the signal line 120A extending in thearrangement direction (Y direction) of the organic light emittingelements 10 emitting the same color light and the second electrode layer16 is avoided in the foregoing embodiment, the application is notlimited to the case. For example, overlap between the scan line 130A andthe power supply line 140A extending in the X direction and the secondelectrode layer 16 may be avoided. In this case, it is sufficient toform a recess or projection extending in the X direction in the overlapregion overlapping the scan line 130A and the power supply line 140A inthe element isolation insulating layer. By avoiding the overlap betweenthe signal line 120A and the second electrode layer 16, the followingtechnical advantages are obtained. Generally, in the case where theplurality of signal lines 120A are provided so as to overlap the commonsecond electrode layer 16 (cathode electrode) in the thicknessdirection, variations often exist in the parasitic capacitance betweenthe signal line 120A and the second electrode layer 16. In this case,parasite capacitances of different sizes (parasite capacitances betweenthe signal line 120A and the second electrode layer 16) are adjacent toeach other. Such variations in the parasite capacitances causevariations in the luminance in the organic light emitting elements 10.When the overlap between the signal line 120A and the second electrodelayer 16 is avoided, occurrence of parasite capacitance between them isprevented. As a result, voltage applied to the signal line 120A iscontrolled, and accurate gradation expression is achieved.

The application is not limited to the materials of the layers, the stackorder of the layers, the film forming methods, and the like described inthe foregoing embodiment. For example, although the case where the firstelectrode layer 13 is used as an anode and the second electrode layer 16is used as a cathode has been described in the foregoing embodiment, thefirst electrode layer 13 may be used as a cathode and the secondelectrode layer 16 may be used as an anode. Further, although theconfiguration of the organic light emitting elements 10R, 10G, and 10Bhas been described concretely in the foregoing embodiment, all of thelayers do not have to be prepared, or other layers may be furtherprovided. For example, a thin film layer for injecting holes made ofchrome oxide (III) (Cr₂O₃), ITO (Indium-Tin Oxide, an oxide mixture filmof indium (In) and tin (Sn)) may be provided between the first electrodelayer 13 and the organic layer 14.

In addition, although the case where the second electrode layer 16 isconstructed by a semipermeable reflection layer has been described inthe foregoing embodiment, the second electrode layer 16 may have astructure in which a semipermeable reflection layer and a transparentelectrode are stacked in order from the side of the first electrodelayer 13. The transparent electrode is provided to decrease electricresistance of the semipermeable reflection layer and is made of aconductive material having sufficient translucency with respect to lightgenerated by the light emission layer. A preferred material of thetransparent electrode is, for example, a compound containing ITO orindium, zinc (Zn), and oxygen for a reason that excellent conduction isobtained even the film is formed at room temperature. The thickness ofthe transparent electrode is, for example, 30 nm to 1000 nm bothinclusive. In this case, a resonator structure may be formed by usingthe semipermeable reflection layer as one end, providing the other endin a position opposed to the semipermeable electrode with thetransparent electrode therebetween, and using the transparent electrodeas a resonator. Further, when such a resonator structure is provided,the organic light emitting elements 10R, 10G, and 10B are covered withthe protection film 18, and the protection film 18 is made of a materialhaving a refractive index similar to that of the material of thetransparent electrode, the protection film 18 serves as a part of theresonator and it is preferable.

In addition, although the case of the display device of the activematrix type has been described in the foregoing embodiments, theapplication is also applicable to a display device of a passive matrixtype. Further, the configuration of the pixel drive circuit for activematrix driving is not limited to that described in the foregoingembodiments. As necessary, a capacitive element and a transistor may beadded. In this case, according to a change in the pixel drive circuit, anecessary drive circuit may be provided in addition to the signal linedrive circuit 120 and the scan line drive circuit 130.

It should be understood that various changes and modifications to thepresently preferred embodiments described herein will be apparent tothose skilled in the art. Such changes and modifications can be madewithout departing from the spirit and scope and without diminishing itsintended advantages. It is therefore intended that such changes andmodifications be covered by the appended claims.

The application is claimed as follows:
 1. A display device comprising: afirst light emitting region and a second light emitting region adjacentto the first light emitting region, each of the first and second lightemitting regions including a first electrode formed on a planarizationfilm, a light emission element formed on the first electrode, and asecond electrode formed on the light emission; a signal line thatpropagates an image signal; a pixel circuit including a first transistorconnected to the signal line, and a second transistor that supplies adriving current to the first electrode; an auxiliary wiring formed onthe planarization film; an insulating element formed on theplanarization film and disposed between the first light emitting regionand the second light emitting region; and a projection formed on theinsulating element and overlapping with the signal line in a thicknessdirection, wherein the auxiliary wiring is electrically connected to thesecond electrode in a region other than the first and second lightemitting regions.